[swift-evolution] Add a `clamp` function to Algorithm.swift

[Nicholas Maccharoli]

Sorry for sidetracking by talking about dumping the global definitions of
`min` and `max` but if that could be done and it were decided by the swift
community that adding a clamp function would be appropriate, I guess with
the array implementations of min / max the clamp function might be
implemented like this?

extension Comparable {

    func clamped(to range: ClosedRange<Self>) -> Self {

        return [range.lowerBound, [self, range.upperBound].min()!].max()!

    }

}

On Fri, Mar 10, 2017 at 5:22 PM, Jaden Geller <jaden.geller at gmail.com>
wrote:

>
> On Mar 9, 2017, at 11:20 PM, Nicholas Maccharoli via swift-evolution <
> swift-evolution at swift.org> wrote:
>
> Nevin,
>
> Yeah I think this works well as an extension on `Comparable`,
>  `foo.clamped(to: 1...100)` seems pretty natural.
>
> Why not go one step further and move the versions of min, max that take
> two arguments on over to `Comparable` as a protocol extension?
>
>
> I think that a symmetric operation like `min` or `max` ought to treat both
> arguments in a symmetric way. `3.max(with: 9)` not only reads badly, but
> privileges one argument over the other syntactically. I’d very much like to
> avoid this.
>
> I would be okay with removing top-level min and max if `Array` min and max
> could generate equivalent code given an array literal. This seems possible.
>
>
> Perhaps something like this?
>
>
> extension Comparable {
>
>     func max(with value: Self) -> Self {
>         if value > self {
>             return value
>         }
>         return self
>     }
>
>     func min(with value: Self) -> Self {
>         if value < self {
>             return value
>         }
>         return self
>     }
>
>     func clamped(to range: ClosedRange<Self>) -> Self {
>         let selfUpperMin = range.upperBound.min(with: self)
>         return range.lowerBound.max(with: selfUpperMin)
>     }
> }
>
>
> - Nick
>
>
> On Fri, Mar 10, 2017 at 1:41 PM, Nevin Brackett-Rozinsky via
> swift-evolution <swift-evolution at swift.org> wrote:
>
>> I’d be on board with an extension of Comparable so you could write
>> “16.clamped(to: 0...10)”. Something along the lines of:
>>
>> extension Comparable {
>>     func clamped(to range: ClosedRange<Self>) -> Self {
>>         return max(range.lowerBound, min(self, range.upperBound))
>>     }
>> }
>>
>> Nevin
>>
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>>
>>
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